Good Dirt for Walnut Trees

Walnuts require deep, well-drained soil.

Walnut trees can grow in a wide range of conditions, but good soil is essential to healthy trees and a bountiful crop. The two most common varieties grown in the United States are black walnut (Juglans nigra) and English walnut (Juglans regia), and both species have similar soil requirements. Black walnut can be grown in U.S. Department of Agriculture hardiness zones 5 to 9, while English walnut can also grow in zone 4.

Depth and Texture

The depth of the soil is important for walnut trees. These trees have a long taproot and should be planted in a location with a soil depth of at least 5 feet. Avoid planting them above underground structures like septic tanks and water lines. Rich, medium-textured loam soil is ideal, and soils that contain mostly sand or mostly clay should be avoided.

Moisture and Drainage

Walnut trees have fairly high water needs and require soil that is moist but well-drained. Avoid locations that are subject to flooding or where standing water gathers after a rain. Drainage is related to soil texture; sandy soils tend to be too dry, while clay soils drain poorly. Walnut trees can withstand periods of drought, but will typically produce a reduced yield under these conditions.

Soil pH

Although they can grow within a wide pH range, with the ability to tolerate either acidic or alkaline soils, walnut trees prefer near-neutral soil, with an ideal pH between 6.8 and 7.2. If you are unsure of your soil's pH, a soil test kit can be purchased at most garden stores. It is possible to raise pH by incorporating lime into your soil, or lower pH by adding elemental sulfur.

Mulching and Fertilizing

The results of your soil test should also reveal the nutrient content of your soil and make recommendations for possible amendments. Walnut trees like soil with lots of organic matter, and adding compost or fertilizer before planting can ensure that they have all the nutrients they need. Adding a layer of mulch above the trees' root zone is also beneficial. Mulch helps walnut trees conserve moisture, protects the roots from cold temperatures, adds nutrients to the soil and reduces competition from weeds.

About the Author

Richard Corrigan has been a full-time professional writer since 2010. His areas of expertise include travel, sports and recreation, gardening, landscaping and the outdoors. He earned a Bachelor of Arts in English from SUNY Geneseo in 2009.